charging rv batteries

[julyer]

my charging method of plugging in the trailer (inverter) night before a short trip doesn't seem to give my two batteries a full charge? would using a battery charger give me a full charge with less time spent charging? here's what i have in a battery charger...battery type (regular and deep cycle)... charge rate ( 2amp, 12amp and 75amp engine start) i don't know how to figure out how much time on the charger is need to full charge one battery? i can't leave the trailer plugged in all the time as it's parked away from power.

[RatherBNtheWoods]

I don't how old your RV is, or which converter you have, but the newer ones charge much better/faster than the typical charger. In the "buckup" mode, mine pushes 65 Amps. It take quite an expensive charger to compete. One full day/night should bring the battery up to full charge. Have you checked alll the connections and the battery itself? I have 2 105A deep cycle and a 85A deep cycle in our Raptor, and each time the turds at the RV shop run ALL the batteries down in the dirt, they are charged by the next morning.
Is the RV battery charging from your truck while you tow it?

[SmokeyWren]

The built in battery charger in most inverters is not really intended to fully charge the RV battery(ies) when they are very low on charge. And the 12-volt charging system when running down the highway with the trailer plugged in is also not really intended to charge the batteries when they are very low on charge. Those chargers are intended to maintain the batteries fully charged while powering the reefer and other electrical stuffat the same time. So you need to charge up the battery(ies) using a battery charger for at least several hours before you hit the road.

If your battery charger is fully automatic, then that's good. Put it on 12 amps and let it charge for several hours. Then change the charging rate to two amps and leave it overnight or until you are ready to hit the road.

If your battery charger is not automatic, then you have to pay attention so you don't overcharge the battery(ies) and ruin them. Charge at 12 amps until the charge is almost full, which will probably require several hours. Then plug in the trailer and let the built-in charger top off overnight before you hit the road.

Charging any battery at any rate more than about 12 to 15 amps will wear out the battery in a hurry. My battery charger is a fully automatic with a trickle charge rate of 2 amps, a slow-charge rate of 12 amps, and then a start charge rate way up there which I never use.

[nitrogen]

you could look for a good solar powered charger to keep it topped off while in storage then it should always be good unless you leave the lights on. i borrowed one of those high tech chargers that send a pulsed current thats supposed to desulphate the battery from my neighbor. at first i wasn't sure but it seems to have freshened up the batteries in the truck, seems like it would be beneficial on the rv batts

[KF6ZVT]

I use a 85 watt solar panel to keep my fivers batteries charged at all times. It is amazing when dry camping, the last trip (10 days dry camping) I used the generator once to run the microwave. I have two 12v deep cycle Optimas, that are about 4 years old and still going strong.

The solar charge controller prevents the batteries from being overcharged. When stored the battery voltage is 13.2 volts, when in use the voltage stays between 12.4 and 13.0 volts. Every night the little woman has to watch at least two DVD's (on a 20 inch TV) and even dries here hair some nights with a 12VDC drier.

[Phillipmc1268]

I'd remove the batteries and charge them at home.

[julyer]

thanks for the info... solar panel would work to keep batteries up when in storage... did you pigtail to both batteries or do you have to switch? the batteries are only couple years old as is the trailer. i do have a small generator...but i don't like to run it unless i'm around...usually busy hunting or fishing and not spending much time at the rv....so i want to be sure the batteries are at full charge before i leave home...long trips to the site isn't a problem...but hauling less than 100mi. doesn't seem to get the batteries fully charged.

[FloridaEd]

I bought one of the knife-blade disconnects for my RV battery. When I get home from a trip and get everything squared away and the unit parked, I flip up the knife switch and totally disconnect one of the battery's poles from the electrical circuit.... effectively isolating the battery. Many months later when I get ready to get ready to go, the battery has plenty of charge to operate the landing feet on the 5'ver. Before I got the knife switch, I took the battery out of the 5'ver and stored it on a wooden bench in the garage.

There's a lot of hidden watt-suckers on modern RV's and they will drain the battery even when you think everything is off.

Florida Ed

[KF6ZVT]

julyer

I put a switch in the circuit from the trailer's built in charger so that I could choose to charge from either source. The charging systems are connected to charge both batteries. The batteries are wired in parallel to provide 12vdc with a lot of amperage capacity.

I forgot to use the switch one time and found that both the solar charge controller and the built-in charger, caused no ill effects to the batteries. I have left both charging systems connected to the batteries for two years now and everything is still OK.

[hiljoball]

Originally Posted by julyer

did you pigtail to both batteries or do you have to switch?

You have 2 batteries. I assume they are 12v deep discharge. They are wired in parallel. To connect to a solar system, just connect the +ve and -ve. There is no need to switch between batteries.

But there is a bit more to it than that. If you have 2 12v batteries in parallel, how are they installed? Is one battery 'behind' the other. and the charger connects to the 'front battery?

This is not the best way and will cause problems as the back battery becomes 'lazy'.

With 2 batteries, it is better to connect the -v to the -ve post of therear battery and the +ve to +ve post of the front battery. This makes both batteries work equally hard. (I call it cross-wired).

Now when connecting the charger or solar, connect the -ve and the +ve to the other two battery posts, This way the charging is also cross wired . .but opposite to the usage side.

Finally, if you let you batteries go down and are not fully rechanged (and it sounds like you have), they should be 'equalized'. This is a process where a charger delivers an overcharge (of about 15 volts) for several hours. This causes the batteries to bubble and shed deposits off the plates and will rejuvinate them.

Most RVs come with a 'Converter/Charger. These are little better than junk. They are 2 state chargers and in spite of their posted rating, provide little more than about 5 amps charge.

A good RV charger is a triple charger and includes an Equalise cycle. A good charger will be able to charge at 60 amps, and then adjust downward as the battery approaches capacity.

[julyer]

Okay... i have two batteries hooked up in parallel. all feeds hot and neg. from trailer are connected to one battery. the other battery just feeds parallel to first battery and both are end to end in front of trailer.... so, if i'm understanding your method of charging...i would hook up from the charger -v to -ve on one battery and +v to +ve on the other battery and both batteries will take the charge? also thanks for the info on equalizing the batteries.

[hiljoball]

That's correct. But also, you should move the -ve line over to the rear battery too. That way both the draw and charge of current goes through both batteries equally.

[the logger]

Sounds to me like your charger/inverter is not putting out enough amps. I camp in the desert of Arizona a few months out of the year. Here's what I do. I use a generator and plug my trailer into it. I then plug in my Vector smart battery charger into the trailer outlet and set it at 20 amps. I only have to do that for about 3 hrs., 3 times a week. I never go to R.V. parks and my batteries hold up fine. Try it.
The logger